Detailed study on Sub grade stabilization by the use of steel slag

Abstract

The goal of this project was to use steel slag in construction projects to stabilize expansive soil for a building which is going to be constructed in Kimihurura Sector, Gasabo District, Kigali City. Different particular objectives led this, including learning about soil classification and carrying capacity, stabilizing soil using by using steel slag in construction projects, and evaluating the function and utility of steel slag in construction projects. The following methods was utilized to accomplish this. Different soil tests were performed on both the non-stabilized and stabilized soils in order to compare the findings; the soil was classed as A-6(9), indicating a fair to poor sub-grade, and the engineering qualities of expansive clays needed to be improved. In this project research, an investigation was carried out to assess the impact of stabilizing expansive soils with steel slag. Research was done on expansive soil sample from Gasabo district at the building site with addition of steel slag in concentrations of 5% steel slag at first trial and 10% steel slag at second trial, each of weight of the soil. For the analysis of the effect of the stabilizers on soil, comparison was made on geotechnical properties of the native soil and stabilized soil which was done by conducting those different tests such as: Sieve analysis, AASHTO classification system, Atterberg limits test, maximum dry density (MDD) by modified proctor test and California Bearing Ratio (CBR) test on both the native soil and stabilized soil. Since 58.2% of the soil is passing through No 200 Sieve, where the soil was classified in silt-clayey material in group of A-6(9) indicating a fair to poor subgrade soil. Before stabilization MDD was 1.82g/cm3

at optimum moisture content of 16.5% and after adding 5% of steel slag, the MDD was increased to the value of 1.96g/cm3

at optimum moisture content of 16%. By adding 10% of steel slag the

MDD increased from 1.96g/cm3

to 2.05g/cm3

at optimum moisture content of 15.7%. CBR value was 4.45 at 95% of compaction before stabilization and after adding 5% of steel slag, CBR value became 8.70% at 95% and for 10% CBR value became 15.0% of compaction which is fair for sub-base to be used in road construction projects. The results indicated that bearing capacity rose on the stabilized soil. As a result of this study, it can be inferred that in road construction projects, the soil must be stabilized with steel slag. Soil stabilization is a crucial process in construction and infrastructure development, which aims to improve the mechanical properties of soil and increase its load-bearing capacity. However, traditional methods of soil stabilization using cement and lime can be expensive, resource-intensive, and have negative environmental impacts. On the other hand, the disposal of industrial waste such as slag is a significant challenge for many industries, as it poses environmental and health hazards. Therefore, finding an effective and sustainable solution to utilize slag as a soil stabilizer could address both environmental and economic concerns